I've read the post before, and I've seen a lot of saying "sched_child_runs_first just not a guarantee of anything". But still, there should be a moment that child process ran first. From my experiment, there was no single time that child process ran before father process. Isn't it interesting ? On Fri, Dec 8, 2017 at 7:18 PM, YU Bo <tsu.yubo@xxxxxxxxx> wrote: > Hi, > > On Fri, Dec 08, 2017 at 11:07:15AM +0800, Rock Lee wrote: >> >> Hi, >> >> I ran my test code but always got the father process run first, even >> after setting sched_child_runs_first. Could anyone give me a hint? >> Here is my test code. >> >> #include <stdio.h> >> #include <unistd.h> >> #include <sys/time.h> >> >> int main(void) >> { >> struct timeval tv; >> struct timezone tz; >> int err; >> pid_t ret = fork(); >> >> if (ret == 0) { >> err = gettimeofday(&tv, &tz); >> if (!err) >> printf("child time sec %d, usec %d\n", tv.tv_sec, tv.tv_usec); >> >> printf("this child.\n"); >> } else if (ret > 1) { >> err = gettimeofday(&tv, &tz); >> >> if (!err) >> printf("father time sec %d, usec %d\n", tv.tv_sec, tv.tv_usec); >> printf("this father.\n"); >> } else >> printf("err!!\n"); >> return 0; >> } >> > > Maybe here: > > https://stackoverflow.com/questions/17391201/does-proc-sys-kernel-sched-child-runs-first-work > > Bo > >> >> -- >> Cheers, >> Rock >> >> _______________________________________________ >> Kernelnewbies mailing list >> Kernelnewbies@xxxxxxxxxxxxxxxxx >> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies -- Cheers, Rock _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies